A Russian investigation into the death of the Palestinian leader Yasser Arafat has found no trace of radioactive poisoning, the chief of the government agency that conducted the study said on Thursday.

Vladimir Uiba, the head of the Federal Medical and Biological Agency, said the agency had no plans to conduct further tests. "It was a natural death – there was no impact of radiation," he said, according to Russian news agencies.

Scientists from France, Switzerland and Russia were asked to determine whether polonium – a rare and extremely lethal substance – played a role in Arafat's death in a French military hospital in 2004. Palestinians have long suspected Israel of poisoning him – a claim Israel denies. Russia, meanwhile, has had close ties with Palestinian authorities since Soviet times when Moscow supported their struggle.

After a 2012 report said traces of polonium were found on Arafat's clothing by scientists in Switzerland, his widow, Suha, filed a legal complaint in France seeking an investigation into whether he was murdered. As part of that inquiry, French investigators had Arafat's remains exhumed and ordered tests on them. Suha Arafat, who was told of the findings this month along with her lawyers, said the French experts found traces of polonium but came to different conclusions than the Swiss about where they came from, finding that they were "of natural environmental origin."

Dr Abdullah Bashir, the head of the Palestinian medical committee investigating Arafat's death, said members were studying the Russian and Swiss reports. "When we finish we are going to announce the results," Bashir said by phone from Amman, Jordan. He wouldn't say when that might be.